Search results for "Atomic Force"
showing 10 items of 308 documents
Synthesis of multi-color luminescent ZnO nanoparticles by ultra-short pulsed laser ablation
2020
Abstract Crystalline ZnO nanoparticles (NPs) are synthesized by ultra-short femtosecond (fs) pulsed laser ablation (PLA) of a zinc plate in deionized water, and are investigated by optical absorption and time resolved luminescence spectra in combination with the morphology and structure analysis. The comparison with previous experiments based on short nanosecond (ns) PLA highlights that pulse duration is a crucial parameter to determine the size and the optical properties of ZnO NPs. While short PLA generates NPs with average size S ‾ of ~ 30 nm, ultrashort PLA allows to achieve much smaller NPs, S ‾ ⩽ 10 nm, that evidence weak quantum confinement effects on both the absorption edge and th…
Second-harmonic Generation Microscopy of Carbon Nanotubes
2012
We image an individual single-walled carbon nanotube (SWNT) by second-harmonic generation (SHG) and transmission electron microscopy and propose that SHG microscopy could be used to probe the handedness of chiral SWNTs.
Microstructuring of phospholipid bilayers on gold surfaces by micromolding in capillaries
2005
Microstructuring of lipid bilayers on gold surfaces was achieved by micromolding in capillaries employing chemically modified polydimethylsiloxane (PDMS). Microfluidic networks of PDMS were prepared by micromolding and functionalized with thiol end-groups using 3-mercaptopropyltrimethoxysilane. The PDMS stamps were firmly attached to the gold substrate via quasi-covalent linkage providing a tight seal, a prerequisite for establishing individual addressable capillaries. Bilayers composed of POPC/POPG were subsequently prepared on microstructured self assembly monolayers of 11-amino-1-undecanethiol via strong electrostatic interactions. This way it is possible to generate individually address…
PAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale Formation
2013
Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4 center dot 2H(2)O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymerization. The derived copolymers had dispersities of 1.3 and below. The copolymers have then b…
Atomic Force Microscopy and Spectroscopy
2021
Atomic force microscopy (AFM) is probably the most celebrated technique falling into the family of experimental methods known as scanning probe microscopy. AFM is primarily designed to obtain the morphology of the surface of a solid material by using the force of interaction between an inert probe and the sample. The AFM microscope can generally be operated in many ways for morphology investigations, but they can be roughly classified into two main groups: static- and dynamic-deflection modes. Since atomic force microscopy makes use of tip-surface interaction to reconstruct the surface morphology of materials, it is of fundamental importance to fully understand the nature and properties of …
Luminescent silicon nanocrystals produced by near-infrared nanosecond pulsed laser ablation in water
2014
Abstract We report the investigation of luminescent nanoparticles produced by ns pulsed Nd:YAG laser ablation of silicon in water. Combined characterization by AFM and IR techniques proves that these nanoparticles have a mean size of ∼3 nm and a core–shell structure consisting of a Si-nanocrystal surrounded by an oxide layer. Time resolved luminescence spectra evidence visible and UV emissions; a band around 1.9 eV originates from Si-nanocrystals, while two bands centered at 2.7 eV and 4.4 eV are associated with oxygen deficient centers in the SiO 2 shell.
High-Density Arrays of Germanium Nanowire Photoresistors
2006
Here we present for the first time a study of the photoresistive properties and dynamics of ordered, high-density arrays of germanium nanowire photoresistors. Germanium is a wellknown semiconducting material with an indirect bandgap, Eg, of approximately 0.66 eV (temperature T = 300 K) and has been widely used for the fabrication of photodetectors, radiation detectors, charged particle and photon tracking devices, far-infrared photoresistors, and numerous other devices. During the last few years there has also been increasing interest in the use of nanostructures (quantum dots and wires) of both germanium and silicon as materials for potential applications in sensors, nanophotonics, and nan…
High-resolution investigation of nanoparticle interaction with a model pulmonary surfactant monolayer.
2012
The pulmonary surfactant film spanning the inner alveolar surface prevents alveolar collapse during the end-exhalation and reduces the work of breathing. Nanoparticles (NPs) present in the atmosphere or nanocarriers targeted through the pulmonary route for medical purposes challenge this biological barrier. During interaction with or passage of NPs through the alveolar surfactant, the biophysical functioning of the film may be altered. However, experimental evidence showing detailed biophysical interaction of NPs with the pulmonary surfactant film are scant. In this study, we have investigated the impact of a hydrophobic polyorganosiloxane (AmOrSil20) NPs on the integrity as well as on the …
Microscopic observation of unworn siloxane-hydrogel soft contact lenses by atomic force microscopy
2006
In the present study, samples of lotrafilcon A, balafilcon A, and galyfilcon A contact lenses were observed by atomic force microscopy (AFM) in tapping mode at areas ranging from 0.25 to 400 m2. Mean roughness (Ra), root-mean-square roughness (Rms) and maximum roughness (Rmax) in nanometers were obtained for the three lens materials at different magnifications. The three contact lenses showed significantly different surface topography. However, roughness values were dependent of the surface area to be analyzed. For a 1 m2 area, statistics revealed a significantly more irregular surface of balafilcon A (Ra = 6.44 nm; Rms = 8.30 nm; Rmax = 96.82 nm) compared with lotrafilcon A (Ra = 2.40 nm; …
Mechanical recycling of polylactide, upgrading trends and combination of valorization techniques
2016
[EN] The upcoming introduction of polylactides in the fractions of polymer waste encourages technologists to ascertain its valorization at the best quality conditions. Mechanical recycling of PLA represents one of the most cost-effective methodologies, but the recycled materials are usually directed to downgraded applications, due to the inherent thermomechanical degradation affecting its mechanical, thermal and rheological performance. In this review, the current state of mechanical recycling of PLA is reported, with special emphasis on a multi-scale comparison among different studies. Additionally, the applications of physical and chemical upgrading strategies, as well as the chances to b…